1. Field of the Invention
This invention relates to attachments for sewing machines, and more particularly to an attachment for sewing machines which converts standard sewing machines to stitch double-knit fabrics.
2. Technical Considerations and Prior Art
When stitching double-knit fabrics, it is necessary to overlap each stitch three times before proceeding to the next stitch. This is, usually, accomplished by advancing the fabric forward to form a first leg of the stitch; reversing the fabric one-stitch length to form a second leg of the stitch and then advancing the fabric forward two-stitch lengths to complete the initial stitch with three overlaps and form the first leg of the next stitch. This procedure is necessary with double-knit fabrics, because double-knit fabrics stretch and thus transfer any force applied to the fabric directly to seams in the fabric. Consequently, seams in double-knit fabrics need to be much stronger than seams utilized in other types of fabric which have structures that absorbs much of the force applied to the fabric.
There are sewing machines currently available which will make the above-described overlapped stitch, however, these machines are relatively expensive and cannot make this stitch in many of the desired configurations such as "satin stitch configurations".
In view of the increasing popularity of double-knit fabrics, there is a need for an attachment which will give any sewing machine the capability of making the overlapped stitch for double-knit fabrics. In order to gain wide acceptance of such an attachment, it is necessary for the attachment to adapt readily to any sewing machine with a minimum of adjustment, and to operate without requiring any change in habit on the part of the user or operator. The prior art does not provide such an attachment.